Mounting of electronic parts at the surface of devices is conducted more widely to rationalize the production and to adapt the production to increases in the type and decreases in the amount. As the form of packaging suited to this mounting, embossed carrier tapes made of a thermoplastic resin are widely used. As shown in FIG. 1, a carrier tape for containing various electronic parts such as semiconductors, parts of high precision instruments and other very small parts has embossed portions 2 as the concave portions for containing the parts which are arranged at the same distance between them in the longitudinal direction in a tape 1 made of a thermoplastic resin, flat rib portions 3 formed between the embossed portions and perforations for transfer of the tape 4 formed at the same distance between them. The tape is used after parts are placed into the concave portion for containing the parts and the tape is sealed with a cover material 5.
The embossed carrier tape is produced by heating the tape at a heating portion and embossing the tape at a molding portion while a long sheet of the tape made of a thermoplastic resin is intermittently transferred by the pitch transfer. Since the number of the part contained in the carrier tape is decided by the pitch of the embossed portions, it is desired that the length in the longitudinal direction of the tape of the rib portion disposed between the embossed portions is decreased so that the number of the contained parts can be increased. Recently, as the size of the electronic parts decrease, the size of the embossed portion decreases and the relative length occupied by the rib portion tends to increase. Since the pitch of the embossed portions is limited to 2 mm, 4 mm, 8 mm or the like by the standard, in some cases, a greater pitch is forced to be used even when the length is changed by about 0.1 mm. The decrease in the length of the rib portion in the longitudinal direction of the tape is very important further due to this situation.
FIG. 2 shows a schematic diagram exhibiting an example of the apparatus for producing a carrier tape. In this apparatus for producing a carrier tape, a long sheet of a tape 6 is supplied from a feed roll 7 and transferred by the pitch transfer using fixing chucks 8 and 9 and transfer chucks 10 and 11, one pitch of the transfer corresponding to the entire length of the mold. The tape is heated at a molding temperature by a pair of heating plates 12 composed of an upper heating plate and a lower heating plate at a heating portion and transferred to the inside of a mold 13 at a molding portion by the pitch transfer. An embossed portion which is the concave portion for containing a part is formed in the tape by heat molding and perforations for transfer of the tape are formed by a punching mold 14 in a punching portion. Finally, the tape is wound by a winding roll 15. For producing a carrier tape having a rib portion having a short length in the longitudinal direction of the tape using the above apparatus, the embossed portions are formed by heat molding under the condition such that the heating portion and the molding portion are disposed as closely as possible to each other. However, it is mechanically limited that the heating portion and the molding portion are disposed very closely to each other and, moreover, there is the possibility that the high temperature at the heating portion affects the molding portion. Therefore, it is impossible that the length of the rib portion is decreased without a limit.
The present invention has an object of providing an apparatus and a process for producing a carrier tape which enables a decrease in the length of the rib portion connecting embossed portions for containing electronic parts and an increase in the number of contained electronic parts.